Vesicular photographic materials and process of forming vesicular images



United States Patent 3,383,213 VESICULAR PHOTOGRAPHIC MATERIALS AND PRUCESS 0F FORMING VESICULAR IMAGES Norman T. Notley and Irwin M. Senentz, In, New Orleans, La., assignors to The Kalvar Corporation, New Orleans, La., a corporation of Louisiana No Drawing. Filed June 14, 1965, Ser. No. 463,940 12 Claims. (Cl. 9649) ABSTRACT OF THE DISCLOSURE The vesicular photographic materials comprising a polymeric material containing dispersed sensitizer. The polymeric materials are polyamides which are soluble in. higher alcohols such as butanol. The preferred materials are polycondensates of a polyamine with polymerized polyene fatty acid. The materials are made :by dissolving the sensitizer and the polyamide in solvents and removing the solvents to form a coating.

The present invention relates to photography and more particularly to the production of vesicular images in water-insensitive photographic materials.

Vesicular images are formed in a photographic film by small bubbles or vesicles of gas which are formed and trapped in the areas of the film exposed to light and which refract light. Generally speaking, the film has a colloid or a resin coating or vehicle .on a backing material and a light-sensitive agent or sensitizer, most commonly a diazo compound, dispersed throughout the coating. When the film is exposed to light, the sensitizer releases molecules of a gas-nitrogen in the case of diazo compounds. These do not form vesicles immediately, but they do so when the film is heated, presumably because the vehicle is relaxed sufficiently on heating for the gas molecules to form bubbles and for the bubbles to expand. The resulting vesicles make the vehicle opaque to transmission of light in the exposed areas and also reflect and scatter light so that they appear white.

The early vesicular materials employed gelatin as the vehicle. These suffered from the difiiculty that the vesicular images obtained faded rap-idly. Later work has revealed that this problem was caused, in part, by the sensitivity of gelatin to water. Gelatin vehicles absorbed moisture from the atmosphere and became soft, thus collapsing the vesicles and destroying the image.

An improvement in vesicular photography which avoided this difliculty is described in US. Patent 3,032,- 414. In that improvement, a vehicle is prepared from certain non-hygroscopic resin materials which are combined with a sensitizer in an organic solvent for the components. A uniform water-free mixture of the components is formed in the solvent and this can be applied to the backing to form the vehicle.

Non-hygroscopic resin materials which are described therein as satisfactory were synthetic, water-insoluble, non-hygroscopic, non-water swelling, highly linear thermoplastic resins selected from the group consisting of homopolymers of styrene, homopolymers of vinyl chloride, homopolymers of vinylidene chloride, copolymers of vinyl chloride with a different vinyl monomer and copolymers of vinylidene chloride with a different vinyl monomenThe vehicles were found to require a permeability constant for nitrogen within the range of 8.6 to 8 10- to avoid escape of the gas before development and nevertheless permit diffusion of the gas to form vesicles during the development. The preparation of the vehicle must also avoid unduly high temperatures and 3,383,213 Patented May 14, 1968 other conditions which lead to the decomposition of the sensitizer.

Another difiiculty with earlier vesicular record materials is sensitivity of the developed image to high temperature. Normally, the image is preserved because the vehicle is rigid and the vesicles are fixed in place. The rigidity of the vehicle is reduced during development to permit gas molecules to diffuse together to form the vesicles and for expansion of the vesicles, but it is thereafter restored by cooling to give permanency to the image. To be truly permanent the vehicle must remain rigid under the conditions to which it is exposed, such as heat and moisture. Resistance is achieved in the improved materials described in the aforesaid Patent 3,032,414, and in the present invention further unexp'e'cted improvements in heat resistance are obtained. In the copending US. patent application of Alfred F. Daech, Ser. No. 191,288, now US. Patent 3,189,455, there is disclosed an improved type of film in which the vehicle is a water/alcohol soluble polyamide such as the one sold under the name Zytel No. 61. These films, when exposed to light and developed 'were shown to have improved image stability on heating.

-It has now been found that a particular class of polya'mides which is soluble in higher alcohols such as butanol, is especially advantageous as a vehicle in the manufacture of vesicular films. More specifically, in accordance with the present invention, vesicular photographic material, for producing a record by light scattering discontinuities within an otherwise optically substantially homogeneous vehicle, comprises a dry film of a hard, fusible, synthetic, thermoplastic polyamide which is soluble in butyl alcohol but insoluble in ethers, esters and ketones, having uniformly dispersed therein a light decomposable agent which is non-reactive to the vehicle and upon exposure to light decomposes into products which are chemically non-reactive to said vehicle and which upon Warming are volatile to form radiation scattering discontinuities only in the light struck areas in said film to thereby furnish said record.

The synthetic polyamide used is the poly-condensate of a polyamine with a polymerized polyene fatty acid or an amide forming derivative thereof. Polymers of this class are fully described, for example, in the Encyclopedia of Che'mical Technology, by Kirk and Othmer, vol. 10 1953), pages 932-937 and US. Patent 2,450,940. Suita'ble polyamides are readily available commercially with molecular weights of about 1,000 and higher. Preferably the molecular weight is at least about 3,000.

Typical acids for such polymers are the dimers of naturally occurring acids derived from soybean, cottonseed and corn oils such as 9, 12 linoleic acid. They may be used directly in the polycondensation or as amide-forming derivatives such as the esters or anhydrides. Amounts of other di-basic acids may be added.

The acids are polycondensed with a polyamine such as ethylene diamine, diethylene triamine, triethylene tetramine, hexamethylene diamine and tetraethylene pentamine, although the polyamides based principally on ethylene diamine are preferred since they may be hard and high melting and have the solubilities indicated above. Polyamides based principally on diethylene triamine are generally tacky and low melting; they are useful for adhesives, but are less desirable for vesicular materials, although they may be employed to advantage in polymer blends.

The light decomposable agents or sensitizers which may be used in vesicular photographic materials are well known and comprise light sensitive agents which are substantially non-reactive to the vehicle, which, upon exposure to light, decompose to form products which are substantially non-reactive with the vehicle and which products are volatile upon warming to produce radiation scattering discontinuities in the vehicle. Of these preferred sensitizers, those which are especially useful are of the type which decompose to release nitrogen on exposure to light, particularly the diazonium salts. Sui-table sensitizers include the diazo compounds which release nitrogen on exposure to light, as disclosed in US. Patents 3,032,414, 2,923,703 and 2,976,145, for example,

p-diazo diphenylamine sulfate,

p-diazo diethylaniline zinc chloride,

p-diazo ethyl hydroxyethylaniline zinc chloride,

p-diazo ethyl methyl aniline zinc chloride,

p-diazo diethyl methyl aniline zinc chloride,

p-diazo ethyl hydroxyethylaniline zinc chloride, 1-diazo-2-oxy naphthaline-4-sulfonate,

p-diethyl amino benzene diazonium chloride ZnCl 4-benzolamino-2,5-diethoxy benzene diazonium chloride, p-chlorobenzene-sulfonate of 4-diazo-l-cyclohexylaniline,

p-chlorobenzene-su1fonate of 4-diazo-2-methoxy-l-cyclo- Other useful sensitizers are those disclosed in British Patent 956,336 published April 22, 1964 and having the general formula C K 2 /O C a in which Y represents hydroxyl, amino, alkylamino, arylamine, or mercapto and Z represents the atoms necessary to form a cyclic structure, and those disclosed in French Patent 1,281,905 having the general structure C ll 0 The vehicle and sensitizer may be combined by any suitable method. It is preferred that they each be dissolved in a solvent, which may be the same or different, and the resultant solutions combined. In this embodiment it is only necessary that the respective solvents be mutually miscible. For the most part, polar solvents will be used such as alcohols. Particularly useful are methyl, ethyl and isopropyl alcohols for the diazo material and isopropyl and butyl alcohols for the polyamide. However, any inert solvent which meets the above miscibility requirements may be used.

The resultant solution is then applied to a backing and dried, for example, by heating in an oven at 240 F. Any suitable backing layer may be used such as polyethylene terephthalate or polyolefin, e.g. polyethylene or isotactic polypropylene. The backing may be transparent or opaque, such as paper. Therefore, it will be appreciated that, while films are specifically referred to herein, all types of photographic elements are contemplated.

After the film is thus prepared, there are at least three different methods of processing it. In one form, the film is exposed to image-forming light, e.g., by being placed in contact with a transparency and exposed to light passing through the transparency. Then, the film is heated to 160300 F. for A to 3 seconds. This will produce an image of the opposite photographic sign from the transparency. Thus, if the transparency is a negative, a positive vesicular photograph will result.

A second processing system which can be used is first described in US. Patent 2,911,299. In it, the film is exposed to image-forming light and gas released by the sensitizer is allowed to diffuse from the vehicle at a temperature too low for development to take place. Then the film is exposed overall to uniform light, which activates undecomposed sensitizer, and is heated to cause development at 160300 F. for to 3 seconds, either during or shortly after the second exposure, but before the gas has substantially diffused from the film. This results in image formation in areas not originally struck by light and an image of the same photographic sign as the transparency. Thus a negative transparency results in formation of a negative vesicular photograph which might be called a reversal image or direct image.

The third processing system is that described in Notley et al. US. patent application Ser. No. 383,169 filed July 16, 1964, now abandoned. In that system, the film is exposed to image forming light of relatively low intensity for at least about 0.5 second and preferably for at least about 2.0 seconds. That is, the light is of low enough intensity that the film does not receive a normal exposure in less than 0.5 second and preferably 2.0 seconds. Then the film receives an overall exposure of light intensity which is suflicient to expose the film in less than 0.2 second and preferably less than 0.01 second. overexposure or longer exposure can be tolerated, but there must be sufiicient light to properly expose the film during the indicated time. This procedure avoids a separate diffusion step as used in the method of US. Patent 2,911,299. In some cases, no heating is required to cause development, and the image appears spontaneously. However, in other cases, some heating may be used to advantage, as more fully described in application Ser. No. 383,169.

A fourth type of processing may also be used which is a modification of the third, but resulting in an image of opposite sign from the transparency or other subject photographed. The first, i.e. the low intensity exposure, is omitted, and only the second exposure with light of high intensity is used. However, unlike the third processing system, overexposure is to be avoided and therefore the exposure will be for less than 0.2 and preferably 0.01 second.

The invention now will be illustrated by specific examples, wherein all parts are by weight, it being understood that no limitation thereto is intended.

EXAMPLE 1 Two separate solutions were prepared from the following materials:

Parts by Solution A Weight Versamid No. 900 1 25 Isopropyl alcohol 80 Parts by Solution B Weight N,N-dimethyl amino benzene diazonium chloride zinc chloride salt 2 Methyl alcohol 40 The solutions were combined and the mixture was coated on a backing of Mylar (oriented polyethylene terephthalate film) and then dried for 5 minutes in an oven which was maintained at 140 F. The film was then exposed through a transparency to light from a 200 wattsecond flash unit.

EXAMPLE 2 A solution was prepared from 25 parts by weight of Versamid 940 1 in 80 parts by weight isopropyl alcohol. This solution was mixed with a solution of two parts by weight of N,N-dimethyl amino benzene diazonium chloride zinc chloride saltin 40 parts by weight methyl alcohol. The resultant solution was coated on a backing of Mylar and dried and the film was exposed as in Example 1.

EXAMPLE 3 The following solutions were prepared:

Parts by Solution A Weight Versalon 1112 1 25 Iso-propyl alcohol 80 Versalon 1112 is a polyamide of the polymerized unsaturated fatty acid characterized by the following properties. Softening point-ball and ring ASTME 28-5803, 110115 0.; viscosity 190 C. 31-44 poises; tensile strength ASTM D1248 GOT 75 F, 1900-2100 p.s.i., 170 R, 500-600 p.s.1., -40 F, 2200-2500 p.s.i,; elongation ASTM D1 248-60T, (5 170 F. 100-500% F. 45%; heat sealing range 85140 0.; izod impact, notched, ASTM D-256-56 ft. lbs/in. of notch 0.2-0.4; pencil hardness 7B, inherent viscosity 86 li in metacresol 0.25; specific gravity ASTM D- 792-601, Method B, 0.955; water absorption ASTM D57- 59a'l after 24: hours 0.07%, after 6 Weeks 0.25%. Taber abrasion resistance NEMA LP22.01 0.0314 gms, wt. loss 100 cycles.

Parts by Solution B Weight N-N-dimethylamino benzene diazonium zinc chloride 2 Methyl alcohol 40 The solutions were blended, applied to Mylar and dried, and the film was exposed as in Example 1.

In the above examples, densities of 0.95 to 1.65 were obtained.

The invention now has been described and illustrated by reference to specific materials and methods. It will be appreciated, however, that various changes may be made with respect thereto without departing from the scope thereof, as defined in the appended claims.

We claim:

1. A photographic material capable of furnishing a record solely in the form of a distribution pattern of radiation scattering discontinuities formed within an otherwise optically substantially homogeneous vehicle, said material being in the form of a dry film, the continuous phase of said film comprising a hard, fusible, synthetic, plastic polyamide which is soluble in butyl alcohol but insoluble in ethers, esters and ketones and a light decomposable agent substantially uniformly dispersed therein as the sole essential image producing agent, said decomposable agent itself being substantially non-reactive to said vehicle and upon exposure to light decomposing into products which are chemically substantially non-reactive to said vehicle and which upon warming are volatile to form said radiation scattering discontinuities only in the light struck areas in said vehicle to thereby furnish said record,

said photographic material being obtained by combining said polymer and said decomposable agent in nonaqueous organic solvent for them to form a uniform, essentially water-free mixture thereof and forming the photographic material by removing said solvent.

2. A photographic material as set forth in claim 1 in W40 is a polyamlde of ethylene diamlne and polymerized unsaturated fatty acid having the following properties: Viscosity at 25 C. (Gardner-Holt) A-C (35% solution in butano1toluene, 1:1) color (Gardner) 12 max. (35% solution in butanol-toluene, 1:1); acid number, approx. 7 1 ash, 0.10% by Weight max.; specific gravityfiOBS pounds per gallon 8.2; penetration at 25 C. (A.S.T. 200 g. weight) approx. 7; ball and ring softening point 105115 C. average molecular weight 3000-6500.

which said polyamide is a polyarnide of polymerized polyene fatty acid with polyamine.

3. A photographic material as set forth in claim 2 in which the polyamine is ethylene diamine.

4. A photographic material as set forth in claim 1 in which said light sensitive agent is a diazo compound.

5. A method of preparing vesicular images comprising exposing to image forming light a photographic material capable of furnishing a record solely in the form of a distribution pattern of radiation scattering discontinuities formed Within an otherwise optically substantially homogeneous vehicle, said material being in the form of a dry film, the continuous phase of said film comprising a hard, fusible synthetic thermoplastic polyamide which is soluble in butyl alcohol but insoluble in ethers, esters and ketones, and a light decomposable agent substantially uniformly dispersed therein as the sole essential image producing agent, said decomposable agent itself being substantially non-reactive to said vehicle and upon exposure to light decomposing into products which are chemically substantially non-reactive to said vehicle and which upon warming are volatile to form said radiation scattering discontinuities only in the light struck areas in said vehicle to thereby furnish said record, said photographic material being obtained by combining said polymer and said decomposable agent in non-aqueous organic solvent for them to form a uniform, essentially water-free mixture thereof and forming the photographic material by removing said solvent, and thereafter heating said photographic material to develop a vesicular image.

6. A method of preparing vesicular images as set forth in claim 5 in which said polyamide is a polyamide of polymerized polyene fatty acid with polyamine.

7. A method of preparing vesicular images as set forth in claim 6 in which said polyamine is ethylene diamine.

8. A method of preparing vesicular images as set forth in claim 5 in which said light sensitive agent is a diazo compound.

9. A method of preparing vesicular images which comprises exposing to image forming light a photographic material capable of furnishing a record solely in the form of a distribution pattern of radiation scattering discontinuities formed within an otherwise optically substantially homogeneous vehicle, said material being in the form of a dry film, the continuous phase of said film comprising a hard, fusible, synthetic thermoplastic polyamide which is soluble in butyl alcohol but insoluble in ethers, esters and ketones and a light decomposable agent substantially uniformly dispersed therein as the sole essential image producing agent, said decomposable agent itself being substantially non-reactive to said vehicle and upon exposure to light decomposing into products which are chemically substantially non-reactive to said vehicle, and upon warming are volatile to form said radiation scattering discontinuities only in the light-struck areas of said vehicle said photographic material being obtained by combining said polymer and said decomposable agent in non aqueous organic solvent for them to form a uniform, essentially water-free mixture thereof and forming the photographic material by removing said solvent,

diffusing said volatile products from said vehicle without forming an image therein, 7 subjecting said photographic material to substantially uniform irradiation to cause decomposition of an additional quantity of said decomposable agent, and heating said vesicular photographic material to cause development and the formation of a vesicular image.

10. A method of preparing vesicular images as set forth in claim 9 in which said polyamide is a polyamide of polymerized polyene fatty acid with polyamine.

11. A method of producing vesicular images as set forth in claim 10 in which said polyamine is ethylene diamine.

12. A method of producing a vesicular photographic 7 8 image as set forth in claim 9 in Which said light sensitive 3,041,294 6/1962 Becke et a1 2602.5 agent is a diazo compound. 3,189,455 6/1965 Daech 9649 XR 3,260,599 7/1966 Lokken 9649 XR References Cited UNITED STATES PATENTS 5 NORMAN G. TORCHIN, Primary Examiner. 2,450,940 10/1948 Cowan et a1 260404.5 BOWERS, Assistant Examiner.

2,703,756 3/1955 Herrick et a1. 9649 

